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Biomedical subjects

R G Mortimer

Publications and source records attributed to R G Mortimer.

At least 37 records · Page 2Linked to original sources
PubMed1989

Older drivers: their night fatal crash involvement and risk.

The 1983 Fatal Accident Reporting System (FARS) data and the Nationwide Personal Transportation Study (NPTS) exposure data were used to describe the major problems in night driving that involved older drivers, aged 65 or more, in fatal crashes and to assess their risk. One of the major findings was that the rate of involvement in fatal crashes in darkness of older drivers was much less than for drivers under the age of 25, but greater overall than for drivers aged 25-64. The rate for older females was much less than for older males. Although the overall fatal crash involvement of older drivers is not a serious cause for alarm at this time, the performance of older males does indicate a substantial increase in risk of fatal crash involvement in darkness. These trends can be expected to become more noticeable over the years as a greater proportion of the population in the United States exceeds the age of 65. The older driver crash involvement at night seems to be particularly troublesome for males in multivehicle crashes where they are struck in the side or rear by another vehicle, and single-vehicle crashes where they run off the road on a straight section. Some suggested improvements of the overall night driving environment are discussed.

Accidents, Traffic↗
PubMed1989

Effect of Actinomyces pyogenes and gram-negative anaerobic bacteria on the development of bovine pyometra.

Fifteen lactating Holstein cows were used in a trial designed to evaluate the effectiveness of intrauterine inoculation (challenge) of Actinomyces pyogenes (A) alone or in combination with Fusobacterium necrophorum (F) and Bacteroides melaninogenicus (B) to induce pyometra. Cows were assigned to one of five groups: A (n = 3), AB (n = 3), AF (n = 3), ABF (n = 3) or C (control, broth medium alone; n = 3). All cows exhibited estrus 12 or 13 d prior to challenge (Day 0=first day of challenge). During the prechallenge period, the reproductive tract of each cow was palpated per rectum and uterine fluid aspirates for culture and uterine biopsies were also obtained. All cows received an intravenous injection of 5,000 IU of human chorionic gonadotropin (hCG; Day 5) and an intrauterine infusion of 40 ml of 0.7% iodine solution (Day 1). Cows were then inoculated on Days 0, 1 and 2 of the experiment. Sequential palpations of the reproductive tracts, samples of uterine fluid for culture and uterine biopsies were performed for a total of 30 d after the first inoculation. A cow was diagnosed as having pyometra when purulent uterine fluid and a corpus luteum were detected by palpation per rectum. The number of cows that developed pyometra in Group A was 2 of 3, in Group AB 3 of 3, in Group AF 3 of 3, in Group ABF 3 of 3 and in Group C 0 of 3. Cows with pyometra did not exhibit estrus. In 7 of 11 cows, pyometra persisted for more than 21 d. In cows that developed pyometra, the same species of bacteria infused into the uterus were usually recovered one or more times during the postchallenge period. When clinical pyometra was diagnosed, histologic endometritis was invariably present. Histologic endometritis and concurrent isolation of A . pyogenes alone or A . pyogenes with gram-negative anaerobic bacteria occurred in 91.7% of samples during the postchallenge period. Regardless of bacterial treatment, gram-negative anaerobic bacteria were frequently isolated with A . pyogenes during this period.

Journal Article↗
PubMed1987

Vesicular adenitis of bulls: A review.

The prevalence of inflammatory disease of the vesicular glands can be as high as 49% in some groups of bulls under common management conditions. Since these bulls are classified as questionable or unsatisfactory potential breeders, this disease can cause significant economic loss to the producer. The current knowledge of the etiology, pathogenesis, diagnosis, treatment, and prevention are discussed.

Journal Article↗
PubMed1987

Control of venereal disease in infected herds.

Losses from trichomoniasis can be controlled by management and treatment strategies. The best strategy for control of campylobacteriosis is vaccination of cows and bulls with a competent vaccine.

Animals↗
PubMed1984

A modified method for complete bovine fetotomy.

A modification of the "Utrecht technique" for complete bovine fetotomy was developed. In cranial presentation, the first step is decapitation, then oblique indirect section through the neck and thorax to remove 1 forelimb with a small part of the thoracic wall. This is followed by thoracic and abdominal evisceration. The final step is direct oblique section of the fetal pelvis or, alternatively, deep detruncation followed by bisection of the pelvis. In caudal presentation, the first step is removal of a hindlimb, then abdominal and thoracic evisceration, followed by thoracic detruncation and oblique section for removal of 1 forelimb and most of the remaining thorax. The neck and remaining forelimb are removed together to complete the procedure.

Abortion, Veterinary↗
PubMed1984

Aspects of bacteriology and endocrinology of cows with pyometra and retained fetal membranes.

In an effort to clarify the pathogenesis of pyometra, 20 cows with retained fetal membranes and 20 without, but with contemporary calving dates were studied. They were palpated and their uteri were subjected to sample collections for bacteriologic cultural examinations twice weekly for 4 weeks. Blood samples were obtained each day and evaluated for serum progesterone concentration. Three cows without and 3 with retained fetal membranes developed pyometra during the study, resulting in 3 groups designated control (CON), cows with retained fetal membranes (RFM), and cows with pyometra (PYO). Bacterial isolations occurred less frequently in the CON group than in the PYO and RFM groups. Growth patterns of bacteria also varied between groups. Coliform and incidental bacteria disappeared from the uterus of the PYO group by the end of the 3rd week. In contrast, heavy growth of Corynebacterium pyogenes and gram-negative anaerobic bacteria developed during this same period in the PYO group. In cows with pyometra, the significant persistent pathogenic bacteria recovered were C pyogenes and gram-negative anaerobic bacteria, especially Fusobacterium necrophorum and Bacteroides melaninogenicus. Anaerobic bacteria were isolated simultaneously with C pyogenes in most cows of the PYO group, but less often in CON and RFM groups, and highest growth levels were present near the time of ovulation. Clinically, pyometra usually developed about 10 days after observation of concurrent ovulation and high growth levels of C pyogenes and gram-negative anaerobic bacteria. A hypothesis is presented for development of pyometra in the cow.

Animals↗
PubMed1983

Serum progesterone concentration in pyometritic and normal postpartum dairy cows.

Two studies were conducted to evaluate the concentration of serum progesterone in pyometritic cows and relate it to palpation of ovarian structures per rectum . In Trial 1, serum samples from 34 pyometritic cows were assayed for progesterone. Mean serum progesterone concentrations were 6.8 +/- 0.7 ng/ml. In Trial 2, each of 54 pyometritic cows was paired with a control cow on the basis of days post partum (18-50 days). Mean concentration of progesterone was 9.7 +/- 1.0 ng/ml for the pyometritic cows and 5.7 +/- 0.8 ng/ml in control cows (P<0.005). Progesterone concentration was greater (P<0.005) in both groups of cows with palpable corpora lutea (CLs). Ninety-six percent of the pyometritic cows had palpable CLs compared to 57% of the control group. Comparing serum progesterone only in cows with a palpable CL, the mean concentration was still greater (P<0.005) in the pyometritic group (10.6 +/- 1.0 ng/ml) than the control group (6.6 +/- 1.0 ng/ml). Compatability of rectal palpation findings and concentrations of serum progesterone were 92.6% for the pyometritic group and 72.2% for the control group. Progesterone concentration increased (P<0.05) by increased days post partum in Trial 2 (n=54) but not in Trial 1 (n=23). In both Trials 1 and 2, uterine size due to pyometra increased (P<0.05) with increased days post partum. No other associations were found.

Journal Article↗
PubMed1980

Elementary transition state theory of the Soret and Dufour effects.

The elementary transition state approach has been used to obtain a simple model theory for the Soret effect (thermal diffusion) and the Dufour effect. The flow of heat in the Dufour effect is identified as the transport of the enthalpy change of activation as molecules diffuse. The theory as now formulated applies only to thermodynamically ideal mixtures of substances with molecules of nearly equal size. The results of the theory conform to the Onsager reciprocal relationship. When the results were fit to data on thermal diffusion for two liquid systems, a close fit was obtained and yielded reasonable values of between 2 and 3 kcal mol(-1) for enthalpy changes of activation and differences between the entropy changes of activation for the two components of between 0 and 1 cal K(-1) mol(-1).

Journal Article↗
PubMed1976

The relationship of bicycle manoeuvrability to handlebar configuration.

Since the handling characteristics of bicycles can affect their safety, the present experiment evaluated the manoevrability of three bicycles which differed only by handlebar configurations: racing (Maes Bend), standard, and high rise. The manoeuvrability of each bicycle was measured as subjects performed six tasks: circle, lane change, figure-eight, straight lane tracking, cornering, and slalom. Subjects were matched by riding experience and grouped by their familiarity with either race or standard bicycle. Analysis of variance showed that no bicycle times bicycle-familiarity interaction effects were significant in any one of the analyses. The performance observed on the bicycles with high-rise and standard handlebar configurations indicated they were not significantly different from each other. On the circle, figure-eight, and slalom tasks, performance with both the high-rise and standard handlebars was significantly better than with the race handlebars. The high-rise showed a slight performance edge on tasks requiring the greatest amount of manoeuvrability, while the standard handlebars offered more control at slower speeds and on tasks requiring stability in tracking.

Journal Article↗
PubMed1976

Fertility of frozen bovine spermatozoa packaged in continental straws or ampules.

Fertility of semen frozen in .25-ml Continental straws or 1.0-ml ampules was compared in two field trials. Semen from four bulls was used to inseminate 574 cows over 38 days in Trial 1. Rates of pregnancy for cows inseminated with semen in straws or ampules were 54 and 32% for first-service inseminations and 70 and 50% at the end of the breeding period. Semen from one bull was used to inseminate 204 cows over 44 days in Trial 2. Rates of pregnancy from single inseminations averaged 58 and 44%, while corresponding values at the end of the breeding period were 83 and 67% for semen in straws and ampules.

Animals↗
PubMed1976

Influence of glycerol concentration and freezing rate on post-thaw motility of bovine spermatozoa in Continental straws.

Semen from each of six bulls was used to study the effects of percent glycerol and rate of freezing on spermatozoa extended in egg yolk-sodium citrate extender and packaged in .25-ml Continental straws. Treatments were arranged factorially and included 5, 6, 7, 8, 9, 10, or 11% (volume/volume) glycerol; freezing rates (time from 5 to -130 C) of 1, 2, 3.5, 7, 12, or 20 min; and post-thaw incubation times of 0 and 2 h at 38 C. Post-thaw motility was similar for spermatozoa frozen in 2 to 20 min, and all means were greater than for spermatozoa frozen in 1 min. Post-thaw motility of spermatozoa frozen in 7% glycerol did not differ from that with 5 to 9% but was superior to that with 10 or 11% glycerol. Although glycerol and freezing rate interacted, 7% glycerol provided survival equal to or greater than that with the other percents of glycerol, regardless of freezing rate.

Animals↗